This invention relates to adsorbents for the removal of trace elements from hydrocarbon stream and a process for their use. More particularly, it relates to an adsorbent for adsorbing mercury, arsenic, sulfur, metal hydrides and related compounds from a hydrocarbon stream, preferably an olefinic or paraffinic stream and a process for its use. This invention also relates to a process for the production of the adsorbent.
Removal of trace elements or impurities from a gas stream is important in the preparation of various hydrocarbon products. Trace elements or impurities, such as sulfur, arsenic, mercury or metal hydrides and compounds which contain these elements, must be removed from gas streams, or they interfere with the production of the hydrocarbon end products. To remove these trace elements or impurities from a gas stream, two different types of products are commonly used: (a) adsorbents to adsorb these impurities or (b) catalysts on which these impurities are chemically reacted.
Adsorbents of this type are described in DE-A-2 319 532. This reference discloses a process for purifying waste gases containing hydrogen sulfide, sulfur dioxide and dust-like sulfur in small concentrations. The waste gases are passed over an adsorbent comprising aluminum oxide or a combination of aluminum oxide and silicon dioxide.
German patent application DE-A-3 719 138 discloses a combustion unit, wherein in order to preserve the activity of a denox catalyst, adsorbents are placed upstream from the catalyst. The adsorbents are designed for the removal of arsenic oxide from the gas stream. The adsorbent products can be used alone or in conjunction with other products. Silica gel, iron oxide, manganese oxide, titanium oxide, molybdenum oxide, alkaline earth oxides and zeolites can be used as an element of the adsorbent.
DE-A-3 029 197 and DE-A-3 029 188 disclose methods for removing hydrogen sulfide from gas mixtures containing hydrocarbons, wherein carbon-containing molecular sieves or activated charcoal are used as adsorbents.
DE-A-2 822 235 discloses a method for removing mercaptan from petroleum distillates whereby the distillants are treated with a weakly basic anion exchanger resin.
DE-A-2 530 091 discloses a method for selectively removing hydrogen sulfide from hydrocarbons wherein a molecular sieve comprising a crystalline zeolite is used.
DE-A-2 356 519 discloses a method for the de-aromatization and de-sulfurization of hydrocarbon mixtures wherein cation exchangers modified with basic nitrogen compounds are used.
DE-A-3 512 352 discloses a method for removing carbonyl sulfide from liquid hydrocarbon feeds. According to this method, the feed is passed over an adsorbent consisting of an anionic ion exchange resin with an amino function.
Arsenic compounds are generally removed from gas mixtures by adsorption. In the past, activated charcoal was generally used for this purpose. Newer adsorbent products for arsenic compounds are disclosed in DE-C-3 816 599 which proposes a method for removing arsenic compounds from waste gases wherein the arsenic-containing waste gas is passed over a sorbent having a large surface area. The sorbent is based on titanium oxide and may, in addition, contain transition metal oxides, such as the oxides of vanadium and/or molybdenum, or tungsten. Furthermore, the sorbent may also contain zirconium oxide and/or clay or silica and/or alumosilicates and/or aluminum oxide.
U.S. Pat. No. 4,729,889 discloses a hydrogen sulfide sorbent which is regenerable. The preferable metals which are included in this product include zinc and iron, copper and iron, copper and aluminum, and copper, molybdenum and iron.
In addition to adsorbent products for the removal of various types of impurities from a gas stream, catalysts are also disclosed for the removal of materials, such as sulfur compounds, including hydrogen sulfide from a hydrocarbon stream. These catalysts are disclosed, for example, by DE-A-2 617 649 which discloses an alumina catalyst which may be impregnated with iron, nickel and/or cobalt.
JP 71-021362 discloses a product for desulfurizing a gas stream utilizing manganese ferrite prepared by mixing an aqueous solution of manganese salt and ferrous salt with an aluminum salt form a co-precipitate of manganic salt and a ferrous salt of an organic-inorganic acid.
JP 71-020688 discloses a gas desulfurization agent using a gamma-iron oxide-based agent.
U.S. Pat. No. 4,489,047 discloses a process for removing hydrogen sulfide from certain process gases using solid acceptors, wherein the acceptors are comprised of an alumina product onto which is placed a metal oxide which may be a manganese oxide or iron oxide, wherein the metal constitutes 2 to 20 percent, preferably 7 to 10 percent, of the acceptor.
A method for removing carbonyl sulfide from liquid hydrocarbon feeds is disclosed in DE-A-2 526 153. In this method, nickel, which is deposited on a carrier, such as aluminum oxide, is used as the catalyst.
DE-A-2 439 234 discloses a method for removing sulfur oxides from gases by means of a catalyst which places an oxide layer of a transition metal on a shaped refractory substrate with small surface area. Both the substrate and the oxide layer may consist of aluminum oxide. Copper oxide is preferably used as the active material because it is sulfated by sulfur dioxide.
DE-A-4 109 312 discloses a catalyst for removing antimony hydride from liquid hydrocarbon compounds containing nickel deposited on a support material.
DE-C-4 224 676 discloses a method for removing mercury from flue gases by contacting the gases with an oxidation catalyst. The metallic mercury portion is oxidized and the ionic mercury is then dissolved in the washing water and is subsequently removed from the washing water by precipitation or adsorption. Generally, a denox catalyst is used as the oxidation catalyst. An additional catalyst for the hydrogenation of acetylene-alcohols is prepared by a process wherein the hydrogenation catalyst contains the oxides of the metals nickel, copper, molybdenum and aluminum and/or iron and may or may not contain manganese oxide.
While many of these products can be utilized for the removal of sulfur products, such as hydrogen sulfide, from a gas stream, it is important that simple, inexpensive adsorbent products be developed for the removal of a broad range of impurities from hydrocarbons streams, especially olefinic gas streams.
Therefore, it is an aspect of the present invention to provide an adsorbent for the removal of trace quantities of sulfur, mercury, arsenic, metal hydrides and compounds containing those elements or compounds, from a hydrocarbon stream, especially an olefinic gas stream.
It is an additional aspect of this invention to develop an adsorbent for the removal of catalyst poisons which may adversely affect the performance of platinum and palladium catalysts used within a gas stream.
It is an additional aspect of the invention to disclose a process for the production of an adsorbent for the removal of trace quantities of sulfur, mercury, arsenic, metal hydrides and mixtures thereof from a gas stream.
It is a still further aspect of the invention to disclose a process for the removal of trace elements of arsenic, sulfur, mercury, metal hydrides and mixtures thereof from a gas stream, particularly an olefinic or paraffinic gas stream.
It is an additional aspect of the invention to disclose a process for removal of impurities from a C1 to C12 olefinic or paraffinic gas stream.
These and other aspects can be obtained by the processes and product disclosed by the present invention.
In accordance with the present invention there is provided an adsorbent useful for the removal of trace elements such as mercury, arsenic, sulfur, metal hydrides and compounds containing those elements or compounds, from a hydrocarbon stream, preferably an olefinic or paraffinic gas stream, more preferably a C1 to C12 hydrocarbon gas stream, wherein the adsorbent comprises about 40 to about 65 percent iron oxide, about 15 to about 50 percent manganese oxide and about 10 to about 20 percent carrier, wherein the carrier is preferably alumina, titania, silica, or mixtures thereof.
The invention is also a process for the production of an adsorbent product for the removal of trace elements of mercury, sulfur, arsenic, metal hydrides and compounds containing those elements or compounds comprising coprecipitating a solution of salts of iron and manganese onto a carrier to produce a preliminary product, which preliminary product is washed, dried and calcined to produce an adsorbent end product comprising about 40 to 65 percent iron oxide, about 15 to about 50 percent manganese oxide and about 10 to about 20 percent support material. Alternatively, the iron oxide and manganese oxide adsorbent product can be produced by impregnation of the metal oxide onto the support material.
The invention is also a process for the removal of trace elements of arsenic, sulfur, mercury, metal hydrides or compounds containing those elements or compounds from a hydrocarbon stream, preferably an olefinic or paraffinic stream, comprising contacting the gas stream with an adsorbent product, wherein the product comprises about 40 to about 65 percent iron oxide, about 15 to about 50 percent manganese oxide and about 10 to about 20 percent support material, preferably aluminum oxide, titanium oxide, silica oxide, or mixtures thereof.